This invention is related to any job requiring human labor. More specifically this invention enables accurate evaluation of the cardiopulmonary demands of a job to be used in both job modification and in job placement.
Historically, the match of individual work to specific jobs was based on a variety of selection processes. In early America for example, slaves were usually more highly valued if they were young, fit and fine physical specimens. The buyers of such workers paid a premium for individuals with the best combination of the attributes. This selection process, while in today""s standards, seems cruel for societal reasons, nevertheless recognized the value of such individuals because the long hours of hard and physically demanding work required only truly fit individuals who could perform such demanding work.
As America""s society was in its early beginning, farms were a large source of laborers. These farmers and cattlemen were accustomed to long hours, hard work and bodies conditioned to such labor as a result of such demanding physical requirements of their lifestyle. In the 1900""s, the supply of young farmers and the like coming to modem factories was large and abundant.
Today""s world of more automated modem facilities and a more sedentary nature of a large portion of the work force make the modem worker more valuable for their ability to run complex machinery and direct work through computer-controlled monitors. It is their ability to be well-educated, skilled workers which is most highly rewarded.
These well-trained and educated employees are valuable and any loss of work due to injuries is even more devastating because such individuals are so productive. In recent years the productivity of workers has year after year increased by one or two percent.
The improved productivity has come about by automating equipment and improving material handling equipment, and redesigning the overall workplace.
While all of these improvements have been beneficial to the economy of the countries employing such advances, it is clear that the skilled and trained workers have an ever-increasing value to the success of the enterprise. Worker absenteeism due to injury is very costly, harmful to the individual and generally a situation that needs to be avoided where possible. The risk of injury to workers can come from a number of sources many of which involve the design of the work, the equipment or the overall work station. Engineers routinely look at these factors and try to design more user-friendly environments to reduce work related injuries.
The individual users are preselected and hired based on the employer""s perception that they are qualified being both mentally and physically capable of performing work. Job applicants have been required to take physical exams, undergo cursory medical tests, and checked for previous work history prior to being hired. This practice has gone on for years. It has been a process of hiring based on the employer""s knowledge of the work he needs done and his experience with other workers that enables him to predict who might be qualified for a certain task. The process of selecting employees who have a high likelihood of being injury free is often times purely subjective. The science of actually knowing what the employer is asking an employee to do is similarly somewhat subjective and relies on past experience.
Gradually, changes have occurred in this process. Recent legislation has tied employment decisions more closely to essential job requirements, and testing against those job requirements is considered valid.
For the most part, workers know they will be asked to perform tasks and that such tasks will be performed over a workday commonly referred to as a shift. Shifts are typically eight to twelve hours and in some cases longer if overtime is requested.
When one asks an employer how much energy is anticipated to be consumed in terms of calories burned per shift or what the total work energy expenditure of the task is that employer is always at a loss for words and yet that is the very nature of a job. Alternatively ask a worker what his working heart rate is during varying periods of exertion or how much air volume he consumes during an eight-hour shift and he too will look puzzled and confused as to the relevancy of such questions.
In this invention, the inventor has determined new and useful ways to evaluate the demands of the job for energy expenditure and cardiorespiratory reserve. Used in conjunction with musculoskeletal demand analysis, job requirements can be set to inform management and prospective employees in ways that allow appropriate and directed testing prior to job initiation.
These measurements are important as they lead to an assessment of endurance and the onset of fatigue. The individual having a known endurance level is less likely to have an injury occur if he or she operates within a work level consistent with his or her capabilities. It is well understood where an individual asks his or her body to perform beyond their capabilities that injury is more likely. When the fatigue or exhaustion factor is introduced or when one exceeds his endurance level mistakes both mental or physical are more likely.
It is in the interest of both the worker and the employer to know in objective terms what is the risk a worker should be allowed to subject his or herself to based on the job requirements and the individual""s capabilities. The present invention provides an improved method to quantify an individual""s energy abilities and cardiac reserve in a cost efficient and practical way. The method further permits equipment and work process involved in performing a task or activity to be quantified in a way that reflects the capabilities of the individual. The combination of these methods permits workers and capabilities to be matched to the job requirements in a more objective fashion than prior art techniques.
A practical and improved method for evaluating the cardiopulmonary demands of work processes or tasks is disclosed. The methodology uses three different modes of analysisxe2x80x94measurement of ventilation, continuous heart rate monitoring, and aerobic capacity testing. By comparison of the results of the three modes, a recommendation can be made as to the level of aerobic capacity required of new job entrants to maximize their ability to perform the job safely. While the modes used are well established in the areas of work physiology, they have not been combined in this practical way to increase validity of the testing in the actual work environment rather than in physiology laboratories. There are software programs that can estimate energy expenditure based on weights and repetition, but they have limited applicability in complex manufacturing tasks.
The first requirement is to understand the pattern and timing of the work, so a decision can be made as to the tasks to be studied. Some jobs have essentially one activity that is done throughout the shift, while others have several in a job rotation. Each major segment is studied while a worker wears an energy expenditure meter, a small mask attached to a microprocessor. This unit measures the air passing in and out of the mouth and nose during a defined period of time. The result is adjusted for the sex, age, height and weight of the tested individual, and reported as liters of air per minute as well as kilocalories of energy used. By previously established formulas, the amount of oxygen required, (which comprises roughly 21% of ambient air) can be calculated.
At the same time, the individual wears a continuous heart rate monitor. When the information from the monitor is transferred to a computer program, several items are calculated which reflect the way the heart has responded to the energy required. The heart rate reserve utilization during the time studied with the ventilation monitor is another physiologic response reflecting how hard this individual was working during that period selected. Because many medications, herbal preparations, caffeine, and tobacco affect the heart rate response, a medical history is taken prior to the testing to identify any confounding factors.
The third comparison made is to the measured aerobic capacity of the individual. The more fit a person is, the more effective their heart is at producing a large volume of blood with each beat. This means that the heart does not have to beat as rapidly to perform a set amount of work, and a lower heart rate results. This person will fatigue less rapidly than a person whose heart has to beat more rapidly to get the work done.
By comparing the results of the oxygen and caloric consumption to the heart rate reserve utilization and the aerobic capacity of individuals in the job, the experienced evaluator can look for consistency and set a level of aerobic capacity for new job entrants that will increase the likelihood of success and productivity.